Electromagnetic transmission



June 25, 1940. y J. ELwx-:LL

ELECTROMAGNETIC TRANSMISSION Filed Aug. 26, 1957 OL H M m Nm El myPatented June 25, 1940 UNITED STATES PATENT OFFICE ELECTROMAGNETICTRANSlWISSION Application August 26, 1937, Serial No. 161,086 In FranceSeptember 7, 1936 11 Claims.

The present invention relates to a revolving mechanism comprisingconsumers of electric current, more particularly to lubricated gearshaving rotating electromagnets, whereby the current is transmitted tosaid consumers or electromagnets by means of a slip ring and a brushsliding thereon.

When using customary carbon brushes having a rotund or rectangular crosssectional congurav tion, the lubricating oil which cannot be preventedfrom. reaching the slip ring forms a thin film between the ring and thebrush and increases the electric transition resistance considerably.This resistance should be as low as posll sible because, for example inthe case of electric motors, the voltage of the exciting current isrelatively low. For example in the case of the starter motor in a motorcar, the current is supplied by a battery and naturally not much tenlsion is available to overcome high resistances. If the slip ring isprotected against oil and held dry, then the brushes are worn out in ashort time because, in order to reduce transition resistance, they mustbe forced to the ring with high presg sure,

It is an object of the present invention to provide a brush which restson the slip ring carrying an oil film. with a ring shaped surface. Withsuch a configuration of the contact surface of 30 the brush, theelectric transition resistance is very low and the life of the brush islong. This may be explained by the fact that the comparatively narrowannular surface presses the oil on a very short path outwardly orinwardly and 35 away from the contact surface of brush and ring withoutnecessitating extraordinary great pressure which would increase the wearon the brush.

In order to insure and control lubrication of the slip ring, the brush,according to the present invention, preferably is of tubularconfiguration and the lubricating oil is supplied to the interior of thebrush. This supply may be carried out through openings in a socket inwhich the brush is slidably located. Any other lubrication of the 45slip ring, for example by spray oil, should be prevented.

With the apparatus according to the present invention, lubrication ismaintained uniform and is easily controlled, the transition resistanceof 50 the electric current is held at a low figure, and the wear of thebrushes is small and their life is long.

Further and other objects of the present invention will be hereinafterset forth in the ac- 55 companying specification and claims and shown inthe drawing which, by way of illustration, shows what I now consider tobe a preferred em.- bodiment of my invention.

In the drawing-- Figure 1 is an axial part cross sectional view of 5 anapparatus according to the present invention.

Figure 2 shows part of what is shown in Figure l in large scale, thebrush being shown in section. 10

Figure 3 is a longitudinal sectional View of a brush according to thepresent invention.

The apparatus shown is particularly suitable for use in motive powerequipment.

Like parts are designated by like numerals in all gures of the drawing.

I designates the casing into which shaft 2 extends. To shaft 2 a disc 2|is keyed which is provided with an annular rim 4 which carries a magnetwinding l0. Rim 4 serves as electromag- 20 netic coupling ring which, ifexcited, pulls the axially movable armature ring' 3 towards itself andthen rotates it, whereby the rotating power is transmitted by friction.The armature ring 3 may also be attracted by means of an annular 26electromagnet 5 having windings 8 and being rigidly connected with thecasing l.

Armature ring 3 is connected to or forms part of a disc the hub of whichcarries a spur gear, which constitutes the center wheel of a planetary30 gear. The outer wheel 'l of said planetary gear is formed by a spurgear which is carried by a member which is carried bythe shaft 2. Saidlast-mentioned member is connected by means of other electromagneticallycontrolled planetary gears with the drive shaft; these gears are notshown as they do not form part of the present invention. The planetarygear wheels 6 are connected with a support which is also keyed to shaft2 and which has a hub on which the afore- 40 mentioned center wheel,which forms one part with the armature 3, is revolvable and slideable inaxial direction. If the windings 8 are excited while windings l0 arewithout current, the center wheel is held stationary. The carrier of theplanetary gear wheels 6, which carrier is keyed to the shaft 2, drivesthen the exterior wheel l. If, however, the windings I0 are excited andwindings 8 are without current, the carrier 'l and the center Wheelrotate at the same speed so that planetary wheels 6 do not rotate. Theexterior gear connected with carrier 'I is then rotated at the samespeed as shaft 2. Current is transmitted to the windings 8 by means ofstationary sockets 9 whereas the supply of current to the 85 rotatingelectromagnets takes place through slip ring and brush.

For this purpose one end of the windings lil is conductively connectedwith ring 4 whereas the other end is connected with the slip ring Il bymeans of an insulated conductor I0. Slip ring II is connected to the hubof the disc-shaped electromagnet having the rim il, and isolatedtherefrom and has a cone-shaped configuration so that oil reaching theslip ring is removed to the left, as seen on Figure l., by means ofcentrifugal forces. Brush I2 rests on the exterior surface of slip ringII.

As is obvious from Figures 2 and 3, brush I2 consists of a tubular bodyof conventional material, for example a mixture oi copper and coal; thebore It of said body widens out towards the lower end of the brushwhereby an annular surface It is formed which contacts slip ring Il.

The tubular body I2 is axially movable in the lower end of the socket I3which may be made of metal and the upper end of which is provided withan interior thread for accommodating the adjusting screw I8.

In between screw IS and the tubular body I2 a coil spring I'I issituated, the tension of which can be adjusted by means of the adjustingscrew I8 and which presses the brush I2 to the slip ring II. Screw I8has a rod-like extension which extends into spring Il for holding thewindings of the latter in place.

The socket I 3 carries at its upper and its lower end bushings lli andIfl respectively made of insulating material. Bushing I is inserted intoan opening of casing I whereas bushing Il sits in a bore of aring-shaped flange IS which forms one piece together with the casing land which serves for covering the slip ring II and protecting it againstoil spray. On disc 2l a ring-shaped flange 20 is provided which pointsoutwardly and is provided with an edge 2t which facilitates throwingaway of oil by centrifugal forces. Edge 2li is arranged as closely aspossible to flange I9 in order to prevent passage of oil towards theslip ring II. v

Above the insulating bushing IQ, socket I3 is provided with radial boresI5.

The operation of the device is as follows: The revolving rim ll and thedisc 3 continuously throw oil towards the casing, which oil runs downthe interior walls of the casing I as indicated by arrows in Figure 2.The oil also wets the exterior of socket I3 and banks up on the upperface of the insulating bushing III. From there the oil enters theinterior of socket I3 through the openings I5 and runs down withinsocket I3 and into the longitudinal bore Iii of the brush I2. In thismanner, the oil reaches the slip ring II within the annular face of thebrush. The small amounts of oil which pass outwardly in between the edgeof the brush and the contact surface of the slip ring flow to the left,as seen on Figure 2, due to centrifugal forces and are thrown ofi theedge 2li so that the slip ring is uniformly covered by a thin lm of oil.

Due to the funnel shaped coniiguration of the outer end of the bore I6,the part actually contacting the slip ring Il is comparatively small.Experience has shown that thereby a low transition resistance isobtained and wear is reduced. This form of the brush also prevents theundesired revolving of the brush in the socket I3.

The exciting current is transmitted to the screw I8 wherefrom it flowsthrough spring Il, holder or socket I3, brush I2, slip ring II andconduit I0 into the windings I0; therefrom the current flows backthrough the steel mass of the magnet. The extent of the lubricationdepends on and is controlled by size and number of the holes I5.

The oil flowing outwardly from the interior of the brush washes the coaldust mud away and also serves for conducting away the heat caused bythefriction of the brushes on the slip ring.

For the supply of oil to the tubular brush holder I3, an oil conduit 23may be connected to the holes I5. One or more radial clearances 22 maybe provided adjacent to the annular contact surface of the brush forbetter washing action of the oil, as are shown in Figure 3.

While I believe the above-described embodi-a ments of my invention to bepreferred embodiments, I wish it to be understood that I do not desireto be limited to the exact details of process, design, and constructionshown and described, for obvious modiiications will occur to a personskilled in the art.

I claim:

l. A revolving mechanism having a rotating slip ring and an electricityconducting brush, said brush having a projecting, comparatively narrowannular surface which amounts to only a small fraction of the brushcross section and which slidingly contacts said slip ring.

2. A lubricated revolving mechanism having in combination a rotatingslip ring and an electricity conducting brush, said slip ring having anouter surface which is inclined with respect to the axis of rotation ofsaid ring whereby the throwing ofi by centrifugal forces of lubricantreaching said ring is facilitated, said brush having a protruding andnarrow annular surface which amounts to only a small fraction of thebrush cross section and which slidingly contacts said inclined outersurface of said slip ring and means associated with said brush forlubricating said annular surface.

3. A revolving mechanism having a rotating slip ring and an electricityconducting brush, said brush having a cavity which widens out at one endwhereby a comparatively narrow annular surface is formed which slidinglycontacts said slip ring.

1i. A lubricated revolving mechanism having a rotating slip ring, anelectricity contacting brush, said brush being of substantially tubularconfiguration and having at one end an annular surface which slidinglycontacts said slip ring, a tubular 1ubricant conduit, said brush beinginserted into said conduit and slidingly movable therein, said conduitconducting lubricant into the interior of said brush, wherefrom thelubricant iiows through said annular surface onto said slip ring.

5. A. revolving mechanism having a rotating slip ring and an electricityconducting brush, said brush having a substantially tubularconfiguration, the interior of said brush being flared outwardly towardsone end of the brush whereby a narrow annular surface is formed whichslidingly contacts said slip ring.

5. A lubricated revolving mechanism having a rotating slip ring, anelectricity conducting hollow brush, a hollow socket slidingly holdingsaid brush in its interior and having openings through which lubricantenters the interior of said socket and therefrom the interior of saidbrush.

7. A lubricated revolving mechanism having a rotating slip ring, anelectricity contacting brush,

said brush beingv of substantially tubular conguration and having at oneend an annular surface which slidingly contacts said slip ring, alubricant conduit connected with said brush adapted to conduct lubricantinto the interior of said brush, wherefrom the lubricant fiows throughsaid annular surface onto said slip ring, stationary shielding meansadjacent to said brush and revolving shielding means adjacent to saidslip ring and to said stationary shielding means, whereby the lubricantis prevented from reaching said slip ring except through said brush.

8. A revolving mechanism having a rotating slip ring and an electricityconducting brush, said brush having an annular surface which slidinglycontacts said slip ring, said annular surface being broken, wherebylubrication and ventilation, i. e., cooling of said brush is improved.

9. A lubricated revolving mechanism comprising a revolving electromagnethaving windings, a rotating slip ring being electrically connected withsaid windings, an electricity conducting brush having a bore opening outinto a cavity at one end whereby a protruding narrow annular surface isformed which slidingly contacts said slip ring.

l0. A lubricated revolving mechanism comprising a casing which housessaid mechanism, a revolving electromagnet within said casing and havingwindings, a rotating slip ring within said casing and being electricallyconnected with said windings, an electricity conducting brush withinsaid casing which brush is of substantially tubular configuration andhas at one end an annular surface, which slidingly contacts said slipring, a rsubstantially tubular lubricant conduit connected with saidcasing and slidingly surrounding and holding said brush and beingadapted to conduct lubricant from said casing into the interior of saidbrush, wherefrom the lubricant flows through said annular surface ontosaid slip rlng.

11. A lubricated revolving mechanism comprising a casing which housessaid mechanism, a revolving electromagnet within said casing and havingwindings, a rotating slip ring within said casing and being electricallyconnected with said windings, an electricity conducting brush withinsaid casing which brush is of substantially tubular configuration andhas at one end an annular surface, which slidingly contacts said slipring, a lubricant conduit connected fWith said brush adapted to conductlubricant ,from said casing into the interior of said brush, Wherefromthe lubricant flows through said annular surface onto said slip ring,stationary shielding means adjacent to said brush and revolvingshielding means connected with said electromagnets and being situatedadjacent to said slip ring and to said stationary shielding means,whereby the lubricant is prevented from reaching said slip ring exceptthrough said brush.

JACQUES ELWELL.

